Dishwashers having phase change materials

ABSTRACT

Dishwashers having phase change materials are disclosed. An example dishwasher for treating dishes according to a cycle of operation includes a tub defining a treating chamber with an opening, a door movably mounted to the tub to selectively open and close the opening, and a phase change material part of at least one of the tub or the door, wherein the transition temperature of the phase change material is below a maximum temperature of the cycle of operation, and wherein the phase change material releases heat during a drying portion of the cycle.

RELATED APPLICATION(S)

This application the benefit of U.S. Provisional Patent Application No. 61/847,181, entitled “Dishwashers Having Phase Change Materials,” and filed Jul. 17, 2013, the entirety of which is incorporated herein by reference.

FIELD OF THE DISCLOSURE

This disclosure relates generally to dishwashers, and, more particularly, to dishwashers having phase change materials.

BACKGROUND

The tub of some dishwashers may be moist or wet at the end of a cycle of operation because they cool during a drying portion of the cycle, which allows water to condense onto them at the end of the cycle. Such moisture may reduce customer satisfaction.

SUMMARY

An example dishwasher for treating dishes according to a cycle of operation includes a tub defining a treating chamber with an opening, a door movably mounted to the tub to selectively open and close the opening, and a phase change material part of at least one of the tub or the door, wherein the transition temperature of the phase change material is below a maximum temperature of the cycle of operation, and wherein the phase change material releases heat during a drying portion of the cycle.

An example method of operating a dishwasher having a tub, a door, and a phase change material that is part of at least one of the tub or the door includes transferring heat energy from the tub to the phase change material by effecting a rapid increase in latent thermal storage by the phase change material, and transferring heat from the phase change material to the tub by effecting a rapid decrease in latent thermal storage by the phase change material.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic, side cross-sectional view of an example dishwasher having a phase change material.

FIG. 2 is a schematic view illustrating an example manner of implementing the controller of the example dishwasher of FIG. 1.

FIGS. 3-5 illustrate example manners of constructing the tub and door of the example dishwasher of FIG. 1 using phase change materials.

FIG. 6 is a graph illustrating example energy storage capacity of a phase change material.

DETAILED DESCRIPTION

In FIGS. 1 and 2, an automated dishwasher 10 according to a disclosed embodiment is illustrated. The dishwasher 10 shares many features of a conventional automated dishwasher, which will not be described in detail herein except as necessary for a complete understanding of this disclosure. A chassis or frame 12 may define an interior of the dishwasher 10 and may include a frame, with or without panels mounted to the frame. An open-faced tub 14 may be provided within the chassis 12 and may at least partially define a treating chamber 16, having an open face, for washing dishes. A door 18 may be movably (e.g., rotationally) mounted to the dishwasher 10 for movement between opened and closed positions to selectively open and close the open face of the tub 14. Thus, the door 18 provides accessibility to the treating chamber 16 for the loading and unloading of dishes or other washable items.

As described below in connection with FIGS. 3-6, the tub 14 and/or the door 18 may be constructed to include phase change materials that rapidly and efficiently release heat energy back into the treating chamber 16 during a drying portion of a cycle of operation, thereby heating the tub 14 and/or door 18 to prevent moisture condensation. As shown in FIG. 6, substantially more heat is released back into the treating chamber 16 by a phase change material than by conventional mastic or other insulating materials. In addition to preventing moisture condensation, the use of phase change materials may increase dishwasher operation efficiency by storing and releasing energy during other phases of a cycle of operation.

It should be appreciated that the door 18 may be secured to the lower front edge of the chassis 12 or to the lower front edge of the tub 14 via a hinge assembly (not shown) configured to pivot the door 18. When the door 18 is closed, user access to the treating chamber 16 may be prevented, whereas user access to the treating chamber 16 may be permitted when the door 18 is open.

Dish holders, illustrated in the form of upper and lower dish racks 26, 28, are located within the treating chamber 16 and receive dishes or other items for washing and/or drying. The upper and lower racks 26, 28 may be mounted to dish rack mounts (not shown) via disk rack rails (not shown) for slidable movement in and out of the treating chamber 16 for ease of loading and unloading. Other dish holders may be provided, such as a silverware basket. As used in this disclosure, the term “dish(es)” is intended to be generic to any item or article, single or plural, that may be treated in the dishwasher 10, including, without limitation, dishes, plates, pots, bowls, pans, glassware, utensils, and silverware.

A spray system is provided for spraying liquid in the treating chamber 16 and is provided in the form of a first lower spray assembly 34, a second lower spray assembly 36, a rotating mid-level spray arm assembly 38, and/or an upper spray arm assembly 40. Upper sprayer 40, mid-level rotatable sprayer 38 and lower rotatable sprayer 34 are located, respectively, above the upper rack 26, beneath the upper rack 26, and beneath the lower rack 28 and are illustrated as rotating spray arms. The second lower spray assembly 36 is illustrated as being located adjacent the lower dish rack 28 toward the rear of the treating chamber 16. The second lower spray assembly 36 is illustrated as including a vertically oriented distribution header or spray manifold 44. Such a spray manifold is set forth in detail in U.S. Pat. No. 7,594,513, issued Sep. 29, 2009, and titled “Multiple Wash Zone Dishwasher,” which is incorporated herein by reference in its entirety.

A recirculation system is provided for recirculating liquid from the treating chamber 16 to the spray system. The recirculation system may include a sump 30 and a pump assembly 31. The sump 30 collects the liquid sprayed in the treating chamber 16 and may be formed by a sloped or recess portion of a bottom wall of the tub 14. The pump assembly 31 may include both a drain pump 32 and a recirculation pump 33. The drain pump 32 may draw liquid from the sump 30 and pump the liquid out of the dishwasher 10 to a household drain line (not shown). The recirculation pump 33 may draw liquid from the sump 30 and the liquid may be simultaneously or selectively pumped through a supply tube 42 to each of the assemblies 34, 36, 38, 40 for selective spraying. While not shown, a liquid supply system may include a water supply conduit coupled with a household water supply for supplying water to the treating chamber 16.

A heating system including a heater 46 may be located within the sump 30 for heating the liquid contained in the sump 30.

A controller 50 is operably coupled with various components of the dishwasher 10 to implement a cycle of operation. The controller 50 may be located within the door 18 as illustrated, or it may alternatively be located somewhere within the chassis 12. The controller 50 may also be operably coupled with a control panel or user interface 56 for receiving user-selected inputs and communicating information to the user. The user interface 56 may include operational controls such as dials, lights, switches, and displays enabling a user to input commands, such as a cycle of operation, to the controller 50 and receive information. In some examples, the controller 50 and the user interface 56 may be implemented in a crown of the door 18 that forms the top portion of the door. Generally, the crown of the door is attached to front and rear panels of the door during assembly/manufacture.

As illustrated schematically in FIG. 2, the controller 50 may be coupled with the heater 46 for heating the wash liquid during a cycle of operation, the drain pump 32 for draining liquid from the treating chamber 16, and the recirculation pump 33 for recirculating the wash liquid during the cycle of operation. The controller 50 may be provided with a memory 52 and a central processing unit (CPU) 54. The memory 52 may be used for storing control software and/or machine-readable instructions that may be executed by the CPU 54 in completing a cycle of operation using the dishwasher 10 and any additional software. For example, the memory 52 may store one or more pre-programmed cycles of operation that may be selected by a user and completed by the dishwasher 10. The controller 50 may also receive input from one or more sensors 58. Non-limiting examples of sensors that may be communicably coupled with the controller 50 include a temperature sensor, and a turbidity sensor to determine the soil load associated with a selected grouping of dishes, such as the dishes associated with a particular area of the treating chamber.

FIGS. 3-5 illustrate example manners of constructing the tub 14 and/or interior surface of the door 18 of the example dishwasher 10 of FIG. 1. FIG. 3 illustrates an example stainless steel tub and/or door 300 comprising a stainless steel layer 305, a phase change material layer 310 and a reflective sheet 315 that reflects heat back towards the stainless steel layer 305.

FIG. 4 illustrates an example plastic tub and/or door 400 comprising a multilayer plastic material (designated in FIG. 4 with two layers 405 and 410) and a phase change material 415 injected between the layers 405 and 410.

FIG. 5 illustrates another example plastic tub and/or door 500 comprising a plastic material 505 having a blanket of phase change material 510 applied to an outside surface of the plastic material 505.

In FIGS. 3-5, the phase change materials 310, 415 and 510 are selected to match expected operating temperatures of the dishwasher 10. For example, the phase change material 310, 415 and 510 may be selected to change phase a few degrees below the highest expected operating temperature in a cycle.

FIG. 6 is a graph illustrating example energy storage capacity 605 of a phase change material. As shown in FIG. 6, as the temperature of the phase change material increases through the phase change transition temperature 610 of the phase change material, the phase change material undergoes a phase change from solid to liquid and undergoes a rapid increase in latent thermal storage capacity Likewise, as the temperature of the phase change material decreases through the phase change transition temperature 610 of the phase change material, the phase change material undergoes a phase change from liquid to solid and releases a large quantity of latent thermal energy. In comparison to the phase change material insulation described in this disclosure, the conventional use of mastic does not allow for the release of large amounts of energy back into the treating chamber 16 as the mastic behaves like a heat sink, which releases its energy over a much longer time frame. Such heat cannot be effectively reclaimed during a traditional 30-to-50 minute drying portion of a cycle. The rapid release of large amounts latent thermal energy back into the treating chamber 16 by the phase change material insulation is how the benefits of the disclosed examples are realized.

Although certain example methods, apparatus and articles of manufacture have been described herein, the scope of coverage of this patent is not limited thereto. On the contrary, this patent covers all methods, apparatus and articles of manufacture fairly falling within the scope of the claims of this patent. 

What is claimed is:
 1. A dishwasher for treating dishes according to a cycle of operation, the dishwasher comprising: a tub defining a treating chamber with an opening; a door movably mounted to the tub to selectively open and close the opening; and a phase change material part of at least one of the tub or the door, wherein the transition temperature of the phase change material is below a maximum temperature of the cycle of operation, and wherein the phase change material releases heat during a drying portion of the cycle.
 2. A dishwasher as defined in claim 1, wherein the phase change material absorbs heat energy during a first portion of the drying portion of the cycle, and releases heat during a second portion of the drying portion of the cycle.
 3. A dishwasher as defined in claim 2, wherein the phase change material absorbs heat energy during a washing portion of the cycle.
 4. A dishwasher as defined in claim 2, wherein the tub comprises a stainless steel layer and a reflective layer, and wherein the phase change material is between the stainless steel and reflective layers.
 5. A dishwasher as defined in claim 2, wherein the tub comprises a multilayer plastic material, and wherein the phase change material is injected into the multilayer plastic material.
 6. A dishwasher as defined in claim 2, wherein the tub comprises two plastic material layers, and wherein the phase change material is between the two plastic material layers.
 7. A dishwasher as defined in claim 2, wherein the tub comprises a plastic material, and wherein the phase change material comprises a blanket applied to an outside surface of the plastic material.
 8. A dishwasher as defined in claim 1, wherein the phase change material absorbs heat energy during a washing portion of the cycle.
 9. A dishwasher as defined in claim 1, wherein the tub comprises a stainless steel layer and a reflective layer, and wherein the phase change material is between the stainless steel and reflective layers.
 10. A dishwasher as defined in claim 1, wherein the tub comprises a multilayer plastic material, and wherein the phase change material is injected into the multilayer plastic material.
 11. A dishwasher as defined in claim 1, wherein the tub comprises two plastic material layers, and wherein the phase change material is between the two plastic material layers.
 12. A dishwasher as defined in claim 1, wherein the tub comprises a plastic material, and wherein the phase change material comprises a blanket applied to an outside surface of the plastic material.
 13. A method of operating a dishwasher having a tub, a door, and a phase change material that is part of at least one of the tub or the door, the method comprising: transferring heat energy from the tub to the phase change material by effecting a rapid increase in latent thermal storage by the phase change material; and transferring heat from the phase change material to the tub by effecting a rapid decrease in latent thermal storage by the phase change material.
 14. A method as defined in claim 13, wherein the rapid increase in latent thermal storage comprises changing the phase change material from a solid to a liquid.
 15. A method as defined in claim 13, wherein the rapid decrease in latent thermal storage comprises changing the phase change material from a liquid to a solid.
 16. A method as defined in claim 13, wherein the transferring of the heat energy from the tub to the phase change material energy occurs during a first portion of a drying portion of a cycle of operating, and wherein the transferring of the heat from the phase change material to the tub occurs during a second portion of the drying portion of the cycle of operation.
 17. A method as defined in claim 13, wherein the transferring of the heat energy from the tub to the phase change material energy occurs during a washing portion of a cycle of operation. 